Flow controlling apparatus for power steering

Abstract

A flow controlling apparatus for a power steering system includes a variable throttle mechanism installed in the pump to change the flow rate of discharged oil from the pump to a hydraulic device; a linear solenoid mechanism controlling the variable throttle mechanism by a predetermined energizing current; a spool feeding back the excess discharged oil to a bypass passage of the pump in accordance with a differential pressure between the upstream and downstream sides of the variable throttle mechanism when the excess fluid exceeds a predetermined value; and an ECU controlling the energized current to change the transition process in accordance with a steering angular velocity of the steering wheel.

1. A flow controlling apparatus for a power steering system, comprising:
 a pump; 
 a hydraulic device receiving discharged oil from said pump to assist a steering wheel by hydraulic power; 
 a variable throttle mechanism installed in said pump to change a flow rate of said discharged oil from said pump to said hydraulic device; 
 a linear solenoid mechanism controlling said variable throttle mechanism according to a predetermined energizing current; 
 a spool feeding back excess discharged oil to a bypass passage of said pump in accordance with a differential pressure between upstream and downstream sides of said variable throttle mechanism when said excess fluid exceeds a predetermined value; and 
 control means for controlling said energizing current to cause said variable throttle mechanism to transition from providing a standby flow rate of said discharged oil to providing an assist flow rate of said discharged oil in accordance with a steering angular velocity of said steering wheel when it is determined that said steering wheel is being turned, wherein said control means controls said energizing current to more rapidly increase said transition from a standby flow rate to an assist flow rate when said steering angular velocity is large, and to more slowly increase said transition from a standby flow rate to an assist flow rate when said steering angular velocity is small, and wherein said control means sets a time constant of an increase of the energizing current to have a small value so that said transition is rapid when said steering angular velocity is large, and sets the time constant to have a large value so that said transition is slow when said steering angular velocity is small. 
 
   
   
     2. A flow controlling apparatus for a power steering system, comprising:
 a pump; 
 a hydraulic device receiving discharged oil from said pump to assist a steering wheel by hydraulic power; 
 a variable throttle mechanism installed in said pump to change a flow rate of said discharged oil from said pump to said hydraulic device; 
 a linear solenoid mechanism controlling said variable throttle mechanism according to a predetermined energizing current; 
 a spool feeding back excess discharged oil to a bypass passage of said pump in accordance with differential pressure between upstream and downstream sides of said variable throttle mechanism when said excess fluid exceeds a predetermined value; and 
 control means for controlling said energizing current to cause said variable throttle mechanism to transition from providing a standby flow rate of said discharged oil to providing an assist flow rate of said discharged oil in accordance with a speed of said steering wheel when it is determined that said steering wheel is being turned, wherein said control means controls said energizing current to more rapidly increase said transition from a standby flow rate to an assist flow rate when said steering wheel speed is large, and to more slowly increase said transition from a standby flow rate to an assist flow rate when said steering wheel speed is small, and wherein said control means sets a time constant of an increase of the energizing current to have a small value so that said transition is rapid when said steering wheel speed is large, and sets a time constant to have a large value so that said transition is slow when said steering wheel speed is small. 
 
   
   
     3. A flow controlling apparatus for a power steering system comprising:
 a pump; 
 a hydraulic device receiving discharged oil from said pump to assist a steering wheel by hydraulic power; 
 a variable throttle mechanism installed in said pump to change a flow rate of said discharged oil from said pump to said hydraulic device; 
 a linear solenoid mechanism controlling said variable throttle mechanism according to a predetermined energizing current; 
 a spool feeding back excess discharged oil to a bypass passage of said pump in accordance with differential pressure between upstream and downstream sides of said variable throttle mechanism when said excess fluid exceeds a predetermined value; and 
 control means for controlling said energizing current to cause said variable throttle mechanism to transition from providing a standby flow rate of said discharged oil to providing an assist flow rate of said discharged oil in accordance with a steering angle of said steering wheel when it is determined that said steering wheel is being turned, wherein said control means controls said energizing current to more rapidly increase said transition from a standby flow rate to an assist flow rate when said steering angle is large, and to more slowly increase said transition from a standby flow rate to an assist flow rate when said steering angle is small, and wherein said control means sets a time constant of an increase of the energizing current to have a small value so that said transition is rapid when said steering angle is large, and sets a time constant to have a large value so that said transition is slow when said steering angle is small.